Software sifts through gravity’s mysteries

Physicists kick off Einstein @ Home campaign

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The Einstein @ Home screensaver shows the source of the data being analyzed as an orange dot on a rotating celestial sphere, with the projected positions of gravity-wave observatories visible as blue and green V-shaped icons.

WASHINGTON — Physicists on Saturday kicked off a campaign to enlist Internet users to help solve one of the biggest unresolved questions surrounding Albert Einstein's general theory of relativity: Do gravitational waves really exist?

Eighty-nine years ago, Einstein predicted that such ripples in space-time should be set off by dramatic cosmic events, such as black hole collisions and stellar explosions. But to date, no one has ever detected the waves. Two sprawling observatories have been set up in the United States and Germany to look for them, but analyzing the data from those efforts requires an enormous amount of computing power.

That's where Einstein @ Home enters the picture.

The screensaver-type program was released to the public on Saturday in conjunction with the American Physical Society's World Year of Physics celebration, marking the centennial of Einstein's initial theories on relativity and quantum physics.

Einstein @ Home uses the same basic platform as SETI @ Home, which signed up more than 5 million computers to sift through radio telescope data for signs of extraterrestrial intelligence. In this case, users can search through data from the U.S. Laser Interferometry Gravitational Wave Observatory, or LIGO, as well as the British-German GEO-600 gravity-wave observatory. The program looks for the faint signals coming from very dense, rapidly rotating compact quark stars and neutron stars — prime candidates for the continuous emission of gravity waves.

Both observatories have only recently undergone enough fine-tuning to detect the signals, if they exist.

What waves could tell
Detecting the waves would allow for deeper testing of Einstein's theories and open up an entirely new avenue for research into the workings of our universe, LIGO director Barry Barish said.

"Does gravity really travel at the speed of light, or is it different from electromagnetic waves?" he asked. "That could be checked, for example, if we saw a signal from these gamma-ray bursts. If we see light traveling a certain speed, you could ask, 'Does the gravitational signal arrive at the same time, earlier, later?'"

In the longer term, gravity-wave study could provide a "completely different way of looking at the universe," Barish said. Such research could help unravel the mysteries of dark matter and dark energy — features that dominate our cosmos but are not yet adequately explained by Einstein's theories.

"The most romantic goal is to be to able to see signals from the early universe with gravitational waves," Barish said. "They would be the most valuable of all, because they're not absorbed like photons or electromagnetic waves are. It allows you to probe back to the very first instants after the Big Bang."

On the other hand, if LIGO and GEO-600 do not detect gravitational waves, that would cast a cloud of uncertainty over general relativity and our understanding of gravity itself.

Einstein @ Home's public unveiling came during the American Association for the Advancement of Science's annual meeting in Washington.

The software has been in beta testing for months, with 10,000 users signed up in advance of Saturday's public release, said the project's principal investigator, Bruce Allen of the University of Wisconsin at Milwaukee. Allen hopes hundreds of thousands of users will join the project.

Versions are available for Windows, Linux and Mac operating systems. Once the program is installed — a process that should take no more than a couple of minutes — it downloads data in the background automatically from a central computer, analyzes the data while a user's computer is idle, then uploads the results back to the server.

Each 12-megabyte chunk of data will be analyzed three times, and the most intriguing signals will be flagged for the project scientists.

"Anything that survives the initial screening ... we can follow up on ourselves," Allen told MSNBC.com.